Daily Archives: June 5, 2013

What’s going on with the Arctic Sea ice?

Since 2001 the amount of Arctic Sea ice that has melted during the summer has generally increased. There may have been a long term trend in melting of ice in the northern hemisphere generally, including mountain glaciers, the Greenland glaciers, and seasonally, Arctic Sea Ice. But the seasonal melting of Arctic Sea ice seems to represent a metastable shift unprecedented in available data. There is probably a tipping point followed by positive feedback. From 2001 onwards, the amount of sea ice melted each summer has gone up, and this has resulted in two related effects: 1) The total amount of sunlight sent back into outer space by reflection from ice and snow has gone down and 2) the amount of warming of the Arctic Sea itself by that non-reflected sunlight has gone up. The result is a graph like this one (hat tip Arctic Sea Ice Blog):

One of several graphs showing the 1979-2001 average for sea ice VOLUME in the Arctic compared to each subsequent year plotted separately.  The present year, with the error bars, is the predicted extent.
One of several graphs showing the 1979-2001 average for sea ice extent in the Arctic compared to each subsequent year plotted separately. The present year, with the error bars, is the predicted extent.

Another view shows the numbers somewhat differently. The grey areas show the confidence limits for the 1979-2012 means, so it includes the reduced years, in volume, with the last four years plotted and the present year shown not as an estimate but as the actual measurement. This shows that we are on track to have a lot of melting:


These data include both good news and bad news, depending on how you want to spin it. The good news is that the seasonal reduction in sea ice volume is not lower then, or not a lot lower than, last years, so maybe we are seeing a leveling off in this phenomenon. The bad news comes in two parts. First, the volume of sea ice includes old ice, which tends to be thicker, and much of that has already melted away, so it can’t melt again because it is already gone. Second, being at the extreme low end of a disturbing trend does not mean that the trend is not disturbing. (See more discussion here.)

Let’s look at extent. This graph from the National Snow and Ice Data Center shows extent (not volume):

Screen Shot 2013-06-05 at 10.41.54 AM


This shows that the current year is on track to look like last year. Notice the big dip last year’s ice took in just a few days from now. It will be interesting to see what the current year’s ice extend does over this same time frame. One of the differences between last year and this year is winds. There was a lot of wind facilitating the breakup of ice last year, but this years the winds are described as “slack.” Related to this, last year June had warmer temperatures over the ice. The last month this year has been relatively cold.

The next four weeks will be interesting to watch.

Dr. Donald R. Prothero has been awarded the 2013 James Shea Award by the National Association of Geoscience Teachers

Hey, check this out:

Dr. Donald R. Prothero recently retired from his professorship at Occidental College in Los Angeles, CA after 27 years of teaching in order to concentrate on his writing and consulting. Dr. Prothero is an indefatigable advocate for geology and paleontology, which he combines with a passion for communicating science to the public. Notably, he has served as a consultant for Discovery Channel, History Channel and National Geographic specials. He frequently gives public talks and presentations to groups interested in Earth science, including presentations to the NYC Skeptics, The Bone Room in Berkeley, CA, Bay Area Skeptics, and the Natural History Museum of L.A. County. Dr. Prothero is a prolific writer; he posts a weekly blog at “Skepticblog” and has published over 30 books. His talks and blogs focus on debunking pseudoscience and defending the science of evolution and climate change. He has made numerous contributions to advancing his fields of expertise by publishing in technical journals. He has authored and co-authored 259 papers, including papers in the following peer-reviewed journals: Nature, Paleobiology, Geology, Palaeogeography, Palaeoclimatology, Palaeoecology, Journal of Paleontology, Journal of Geology, Science, Journal of Geological Education, Palaios, Paleoceanography, and Geotimes to name a few. Prothero has served as a reviewer and editor throughout his career. He served as adjunct editor for Paleobiology and he has also served on the editorial boards of Skeptic magazine and for Geology. In addition, he has served as technical editor for Journal of Paleontology and as a consulting editor for the McGraw-Hill Yearbook of Science and Technology. In recognition of Dr. Prothero’s exceptional contributions in the form of writing and editing of Earth science materials, NAGT is proud to award him with the 2013 James Shea Award.

See also: Greenhouse of the Dinosaurs and Donald Prothero Radio Interview.

And, some of Donald Prothero’s other books:

Evolution: What the Fossils Say and Why It Matters

Rhinoceros Giants: The Paleobiology of Indricotheres (Life of the Past)

Abominable Science!: Origins of the Yeti, Nessie, and Other Famous Cryptids

Reality Check: How Science Deniers Threaten Our Future

After the Dinosaurs: The Age of Mammals (Life of the Past)

Catastrophes!: Earthquakes, Tsunamis, Tornadoes, and Other Earth-Shattering Disasters

Bringing Fossils To Life: An Introduction To Paleobiology

Sedimentary Geology

The Evolution of Artiodactyls

The Terrestrial Eocene-Oligocene Transition in North America